AdaIC News Spring/Summer 1996

Ada 95 Update

Airfields: An Ada 95 Success Story

| Project - Airfields | Training |
| Ada 95 - New Features | Teamwork |

Hierarchical library units made development easier, ....the developers could map their Ada 95 code naturally to the structure of the underlined RDBMS.

Project - Airfields

On January 5, 1996, the Defense Information Systems Agency (DISA) delivered what is apparently the first completed project written in Ada 95.

The project is Airfields, one of the first Early Ada 95 Adopter efforts assisted by the Ada Joint Program Office (AJPO); part of the Global Command and Control System (GCCS), DISA's new integrated command and control environment, it was accepted by GCCS on 16 Mar.1996.

Airfields provides commanders with access to many different kinds of information about airfields and airports worldwide. (For details, see the Summer 1995 AdaIC News.) Delivery culminated a year-long effort to convert this information system -- and its developers -- from COBOL to Ada 95. (The COBOL version of Airfields is part of the World Wide Command and Control System -- WWMMCS.)


Teamwork and adaptability were key factors in the success of this project. The Airfields team dealt with limited resources, tight staffing, and Ada 95 bindings issues early in the process; in each case, the team adapted and put Ada 95's strengths to work.

One of the major reasons for this project's success was the ability of the programmers to quickly grasp Ada 95. Since the majority of the programmers were trained in COBOL, the AJPO provided the team with mentors and training in Ada 95. The mentors were impressed with the speed with which the programmers picked up Ada 95 without previous Ada experience.

Ada 95 -- New Features

Looking back, using the new features of Ada 95 was one of the biggest advantages to the Airfields team, according to Airfields Team Leader Velma Blue. Features such as hierarchical library units (HLUs), unbounded-length strings, and tagged types significantly increased the speed with which the project was developed. For example, HLUs made development easier because they allowed developers to map their Ada 95 code naturally to the structure of the underying RDBMS.

Heavy use of the new unbounded-length string feature was also helpful. Unbounded strings were used to display the reports on the screen. The majority of the Airfields data records had variable lengths; with unbounded strings, the team did not have to worry about the size of the reports. In addition, using unbounded-length strings meant the developers did not access wasted space when retrieving and manipulating the data.

Tagged types were used to manipulate the data based on the user's selection criteria. Selection criteria narrowed down retrievals for specific report generation. Ada 95's tagged types allow all of the selection criteria to be processed correctly by dynamically selecting the appropriate Ada subprogram to process the user's selection criteria.


Teamwork was vital both within the team and between the team and the AJPO-provided mentors. The team had to find an Ada 95 binding that would work with their compiler, GNU Ada 95 Translator (GNAT). The research for binding was undertaken by the mentors who assisted the team in moving up to Ada 95. Without waiting for the final conclusion of what binding to use, the team moved ahead on its re-engineering effort, in the hope that one would be located by the crucial time the binding would be needed. They discovered that AdaConnect, an Open Data Base Connectivity (ODBC) product by Objective Interface Systems (OIS), worked with both GNAT and Oracle. After selecting AdaConnect, integration was "seamless", said one mentor.

Velma Blue, Airfields Team Leader, summed up the Airfields effort: "Working on this project has been a unique experience for me. There were many challenges to face and many obstacles to overcome. I am thrilled that all have been resolved. I could not have done it without the support of the team. The team had a 'can do' attitude. The most beneficial experience for this project was the access to and the utilization of expert support from the AJPO mentors."

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